1. Field of the Invention
The present invention relates to a process for producing a useful bismuth compound used in electric devices such as ferroelectric memory etc. as well as to a dielectric ferroelectric of a bismuth compound.
2. Description of the Related Art
The bismuth-layered compound forms a group of industrially extremely important compounds such as bismuth series superconducting oxides with a critical temperature of 110 K, or materials for ferromagnetic memory etc. For application of these compounds to electric devices, it is essential to develop a thin film process.
The structure of this bismuth-layered compound is found in e.g. Bi.sub.2 PbNb.sub.2 O.sub.9 and is represented by a repeating structure in a pseudo-tetragonal system having a layer of bismuth oxide and a layer of an oxide of another element laminated repeatedly in a definite order and extended in column shape along the c axis direction (see G. A. SMOLENSKII et al., SOVIET PHYSICS-SOLID STATE, pp. 651-655 (1961)) and E. C. SUBBARAO, J. Phys. Chem. Solids Pergamon Press, Vol. 23, pp. 665-676 (1962)).
In this repeating structure, the number of bismuth oxide layers in 1 unit structure and the length of 1 unit structure vary depending on an individual bismuth-layered compound.
At present, the application of this bismuth-layered compound to electric devices is attempted, and in such an attempt, a thin layer of a bismuth-layered compound excellent in ferroelectric properties is obtained by spin coating methods including metal organic decomposition (MOD) etc.